Microphone-transmitter.



A. A. JAHNKE. MICROPHONE TRANSMITTER. APPLICATION FILED Nov. 18. 1910.

Patented Oct. 24, I911.

INVENTOR Mam (/5 ATTORNEY UNITED STATES PATENT orr cn.

ALBERT A. JAnuKn, or mcnmom), CALIFORNIA, ASSIGNOR, BY 'MEsNn ASSIGNMENTS, 'ro NATIONAL WIRELESS TELEPHONE & TELEGRAPH 00., A 'conronArIoN or r111:

TERRITORY OF ARIZONA.

To allwhom it may concern.

Be it known that;I,.ALBERT A. JAHNKE, a citizen of the United States, residing at Richmond, in the county of Contra Costa and State of California,'have invented new and useful Improvements in Microphone- Transmitters, of which the following is a specification. Y

The present invention relates to improvements in microphone transmitters, the object of the invention' being to provide a device of this character in which an exceedingly large transmission current can be used, variations in said current being produced by the vibrations of the transmitter diaphragm Without unduly heating that portion of the transmission circuit in which the resistance is varied.

In the accompanying drawings, Figure 1 is a vertical sect-ion of'the transmitter; Fig. 2 is a broken rear view of the same. I

Referring to the drawing, 1 indicates a casing, within which is secured, by screws2,

- a flange 3 of-a disk 4, to which is secured the mouthpiece-5. Secured within said flanged disk 4 by a threaded ring 6 are rings 7 of insulating material such as lava, which will withstand great heat, between which rings 7 is clamped the edge of a circular diaphragm 8 of suitable material suchas aluminum capable of vibration. Within the casing 1 is contained an annular receptacle 10, made of light material, such as macadamite or -aluminum, and formed ofsections, secured by screws 12. Between an inner annular wall 13 of said receptacle and the. side walls l t-thereof are clampedtwocir .cular sheets 15 of mica. Through a large central hole in each sheet is passeda cooling receptacle, the receptacle 16', nearest to the diaphragm extending forward .;toward said diaphragm, and the receptzicl'l'? re mote therefrom extending rearward from said diaphragm. Each receptacle has a flange 18 abutting against the corresponding mica disk, and the two opposing sides of ,said receptacles are covered with a facing-'19 of an iridium platinum alloy. Thereceptacle 17' is formed with a tube 20 extending therefrom, which is clamped between-metal yokes 21 secured by screws 22 to the flange 3, said yokes being screwed togethel by screws 23, insulating material 24,]such as lava, being interposed between said tube and MICROPHONE-TRANSMITTER.

yokes. Th receptacle 16 is movable, having a tube 25 extendingoutwardly therefrom and passing through a central hole in the diaphragm 8, said .tube having a shoulder 26 abutting against said diaphragm, and there being screwed on said tube against said diaphragm. a'nut 27. The space within the internal wall 13 and between the two mica disks 15 and the two iridium-platinum facings 19 is filled with carbon granules. con: ducting wires 28, 29, are connected, the one to the receptacle 16 and the other to a partof thetube 20' which extends outside the casing 1.

The following is the mode of use of the transmitter. A heavy current is passed through said wires, thevariable resistance portion of the circuit of said current cor sisting of the carbon granules between the iridium platinum facings or terminals 13. Upon talking into the mouth-piece, the diaphragm 8 is set in vibration, which pro duces corresponding vibration of the receptacle 16 and of the facing 19 carried therespecification of Iiettersratent. Patented ect, 24,1911, Application filed November is, 19 1o.- Seria1No. 5.'-32,951.

by. The other facing being stationary, the

distance between said facings and consequently the resistance to the passage of the electric current is varied with the vibration of the diaphragm. It is, of course, very old in the art to use auditory vibrations of a diaphragm to vary the resistance of carbon granules in order to vary the current passed through said granules. Heretofore, how ever, 1t has not been possible to use a large current as the means for transmitting such vibrations for the reason that a large cur-.

rent unduly. heats the carbon granules andcauses them to fuse and adhere together.

My invention consists in the means for preventing this result. V For this purpose, there are attached to the tubes 20 and 25 rubber tubes 31, 32, through which a liquid, as alcohol, flows into the. receptacles 17, 16,

said liquid flowing out by pipes 33, 34, connected with rubber tube 35, 36. In like manner-t-he annular receptacle 10 is'filledwith alcohol by a pipe 37 leading thereto connected with a rubber tube 38 and the alcohol escapes therefrom at the top by a pipe 39 connectedwith a rubber tube 40. It is nec essary that the outlet pipes should be at the top of the several receptacles in orderto insure their being filled at all-times. The

inletlpipes can lead from. a suitable tank il-Ywloich' can befilled from time to'time, '1 heoutlet pipes in like manner discharging into a suitable receptacle 42.

The inner wall'l3 of the annular receptaole is madeof what is known as lavite, the

chemical composition'of which is Z aS 'l a H material when cool is not porous, -or at least not sufiiciently so to permit a liquid to escape theret hrough,but when heated it is suificientlyporous' to permit alcohol vapor in the'aimular chamber,10 'to escape there through; This alcohol vaporesc'aping into the chamber containing the carbon granules has the. efiect of'cooling said granules but its principal function is to reduce the electric' resistance between the iridium platinum ,facings 19. When said .facings approach 'each othe'rby the auditory vibrations of the diaphragm, the alcohol vapor is pushed outward from 'between vsaid facin s andthroughthe pores ,of the surrounding wall 13, and when they re'cede from each other it. is, for the" same reason, .sucked inward.

-,This movement takes place in the same rapid succession as the vibrations of sound. The

' result a constant variation in the variable resistance portion of-th'e electric circult and therefore a constant variation in the current produced in the transmission circuit.

, I claim 1. The combination of .two terminals in an electric circuit, carbon granules between said termiiials, a receptacle for a volatile liquld, a porous wallfor said receptacle and 'separating 'it from the carbon granules, a diaphragm for receiving sound vibrations,

' and-a connection between said diaphragm and oneof said terminals, whereby the dislow poles, a receptacle for a volatile liquid,

mower tancebetween the terminals is'varied With the vibration of the diaphragm, and means for maintaining a clrculation of said liquid through said receptacle, substantially as described. 4 2. The combination of two hollow termi' nals in an electric circuit, carbon granules between said terminals, means for maintaining a circulation'of liquid through said hola porous wall. for said'receptacle and sepai rating it from the carbon granules, a dia-' between said terminals, means for maintaining a. circulation of liquid through, said hollow poles, a receptacle fora volatile liquid,

a porous wall for said receptacle and sepa-- rating it from the carbon granules, 'a diaphragm for receiving sound vibrations, fiexiblenwalls for inclosing said carbon granules,

each wall connecting the, porous wall with oneof the terminals, and aconnection betweensaid diaphragm and one of said ter- 7 -minals, whereby the distance between the terminals is varied with the'vibration of the diaphragm, substantially as described,

In testimony whereof I have hereunto set myhand in the presence of two subscribing witnesses.

-. ALBERTA. JAHNKE.

Witnesses:

FRANCIS M. WRIGHT.

D. B. RICHARDS; 

